1. Field of the Invention
The present invention relates to a sterilizing and disinfecting apparatus for use in sterilizing and disinfecting a target space by spraying a sterilizing and disinfecting chemical including high-concentration alcohol into the target space.
2. Description of Related Art
As one example of a method of efficiently sterilizing and disinfecting spaces where high cleanliness is required, such as clean rooms of pharmaceutical companies, food factories, wards of hospitals, the inside of ambulances and kitchens of food shops, for example, Japanese Examined Patent Application Laid-Open No. 6-84287 (1994) and Japanese Unexamined Patent Application Laid-Open No. 2000-237288 propose methods in which a sterilizing and disinfecting chemical including alcohol as a main component is sprayed in the form of fine particles.
These methods use a spray gun which is widely used for various painting operations. A chemical tank containing the above-mentioned chemical is attached to the spray gun, and a gas cylinder containing a carrier gas for spraying is connected to the spray gun. The carrier gas supplied from the gas cylinder is injected from the end nozzle of the spray gun, and the chemical in the chemical tank is sucked by a function of the negative pressure created at this time and is sprayed together with the carrier gas.
At this time, by using a carrier gas that does not react with alcohol, such as carbon dioxide gas and nitrogen gas, so as to isolate the sprayed alcohol from oxygen in the space, a high sterilizing and disinfecting function of alcohol can be obtained while avoiding the risk of ignition immediately after spraying. Moreover, by setting an injecting pressure of the carrier gas to control the particle size of the sprayed chemical, it is possible to optimize the settling velocity of the chemical particles in the sprayed space. It is therefore possible to spread the chemical particles throughout the target space including the corners of the space by short-time spraying, and to evenly and satisfactorily sterilize and disinfect the target space. Furthermore, since the sprayed chemical in the form of fine particles includes high-concentration alcohol with quick dry characteristics as a main component, the chemical will evaporate rapidly after adhering to the wall surface, floor surface and the like in the target space without remaining for a long time, and thus there is no need to perform a post treatment including wiping.
On the other hand, when spraying a chemical including alcohol, care must be taken so that the concentration of alcohol in the sprayed space does not exceed the explosion limit. According to the above-described method, however, since the sprayed chemical diffuses evenly throughout the target space, it is possible to achieve the object under a sufficiently low concentration than the explosion limit. Moreover, even in the periphery of the end nozzle of the spray gun, it is possible to maintain an appropriate mixed ratio of the chemical and the carrier gas, and to realize a sprayed condition in which the chemical particles are covered with the carrier gas, by optimizing the design of the end nozzle. It is therefore possible to completely eliminate the risk of explosion, and perform the sterilizing and disinfecting operation without taking into account the presence or absence of fire in the target space.
As described above, the sterilizing and disinfecting methods disclosed in Japanese Examined Patent Application Laid-Open No. 6-84287 (1994) and Japanese Unexamined Patent Application Laid-Open No. 2000-237288 are excellent methods capable of sterilizing and disinfecting any target space in a highly efficient and satisfactory manner. However, these methods use a liquefied gas cylinder filled with carbon dioxide gas or nitrogen gas in a liquefied state as the gas source of carbon dioxide gas or nitrogen gas that serves as a carrier gas, and the liquefied gas supplied from the liquefied gas cylinder is heated and vaporized by a heater and then decompressed to a required injecting pressure to obtain a desired carrier gas. These methods have the following problems.
First, heating with the heater is performed so as to prevent the peripheral part from freezing due to a decrease in temperature caused by volume expansion resulting from the decompression afterward. For this purpose, it is necessary to have the heater and control means for controlling the temperature of the heater and also an anti-freezing mechanism, such as a fin for absorbing heat from outside air in the periphery of the decompression section, and consequently the configuration of the apparatus is complicated.
Second, it is essential to secure a power supply for supplying power to the heater, and thus the place where the apparatus can be used is limited. Besides, if the apparatus comprises an internal power supply, the configuration of the apparatus is further complicated.
Third, a liquefied gas cylinder designed to supply a liquefied gas, i.e., a so-called siphon type liquefied gas cylinder, is originally manufactured to utilize low temperatures of the liquefied gas, and is commercially sold as a large cylinder with a content capacity of 10 Kg or more and a total weight of 20 Kg or more. It is difficult to move a conventional sterilizing and disinfecting apparatus using such a liquefied gas cylinder, even when the apparatus is mounted on a transport truck. Therefore, for example, when sterilizing and disinfecting a plurality of wards of a hospital or the inside of a plurality of ambulances, hard work is required to move the sterilizing and disinfecting apparatus to the respective locations.